Table type display device

ABSTRACT

A table type display device, in which a high resolution display with an unremarkable connection is realized at the time of large screen display by using a screen with a composition having few bending is described. In a table type display device comprising plural M of projectors  1 L,  1 R for projecting luminous flux to form an image, plural N of reflection mirrors  2 L,  2 R for bending optical paths of luminous fluxes projected from respective plural M of projectors  1 L,  1 R, screen  3  of horizontal installation type for projecting luminous fluxes for which optical path is bent, by the plurality N of reflection mirrors  2 L, 2 R onto the predetermined region, respectively, the screen comprises a transparent base member  7  for reducing flexure of the screen, optical sheet  9  substantially for making luminous fluxes projected respectively from the plural M of projectors  1 L, 1 R uniform, and a diffusing screen for imaging the image.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a table type display devicecapable of achieving high resolution display at the time of displayingthe large screen, by projecting luminous flux for the image formationfrom a plurality of projectors on the screen of the horizontal locationtype.

[0003] 2. Related Art Station

[0004] As a conventional table type display device to project theluminous flux to form the image on the screen of the horizontal locationtype, for example, there are the device of the type displaying images onthe LCD panel, and device of type shown in FIG. 18, by burying one LCDpanel of the order of 10-14 inches in a horizontal plane of a table-likecasing. The conventional table type display device shown in FIG. 18corresponds to the device described in FIG. 3 of Japanese PatentLaid-open No. 305,079/2000, and comprises one projector 51 forprojecting luminous flux to form-an image, two reflection mirrors 52 and53 for bending an optical path of luminous flux projected from theprojector 51 twice, and a transparent screen 54 of the horizontallocation type, from which luminous flux bent two times, is projected toan optical path by these reflection mirrors 52 and 53, which are builtin a same casing 55, the casing 55 is constituted in the shape of thedesk, and a transparent screen 54 constitutes the desk plane (tableplane).

[0005] The conventional table type display device shown in FIG. 18adopts a construction in which the luminous flux projected from oneprojector 51 is projected through tow reflection mirrors 52 and 53 on atransparent screen 54, so that resolution of the projector anddisplaying resolution on the screen are the same. Therefore, forexample, even in case of utilizing a projector with the resolution ofXGA (1024×768 pixels), the resolution on the screen becomes only XGA,and when the screen is made a large screen, the displayed image ratherbecomes unclear and becomes hard to see. Therefore, in the aboveconventional display device, it is difficult to achieve the highresolution display at the time of displaying the large screen.

[0006] In the display device, as a method of achieving high resolutiondisplay at the time of displaying large screen, for example, asdescribed in Japanese Patent Application Opened No. 326981/1997, whichhas been filed previously by the present applicant, there is a method ofdisplaying one image on the entire screen, by projecting the luminousfluxes to form the images from a plurality of projectors to apredetermined region of the screen constituted to the large screenrespectively.

[0007] When the screen constituted to the large screen, is horizontallylocated to constitute the table type display device, the screen is bentby the self-weight of the screen, and is bent by loading a part or allof the weight of the viewer on the screen. In that case, the displayimage is distorted and blurred, and thus the display quality isdeteriorated, so that the flexure of the screen must be reduced.

[0008] Moreover, in case of projecting the luminous flux to form theimage from a plurality of projectors to a predetermined region of thescreen constituted to the large screen, respectively, the incident angleof luminous fluxes in the periphery of respective regions becomes largecompared with the incident angle of luminous flux in a central portionthereof, so that the boundary of the adjoining area looks dark, and theconnection stands out, and thus the visual performance of the displayimage is different according to the standing position of the viewer.

SUMMARY OF THE INVENTION

[0009] The present invention has for its first object to provide a tabletype display device for realizing high resolution display at the time ofdisplaying the large screen, by using a screen with construction of lessbending. The present invention has for its second object to provide atable type display device for realizing high resolution display withunremarkable connection at the time of displaying the large screen, byusing a screen with construction of less bending.

[0010] In order to achieve the above first object, the first inventionas claimed in claim 1 is a table type display device comprising plural Mof projectors for projecting luminous flux to form an image, plural N ofreflection mirrors for bending optical path of luminous flux projectedfrom respective plural M of projectors, screen of horizontalinstallation type for projecting luminous flux for which optical path isbent, by the plurality of reflection mirrors N onto the predeterminedregion, respectively, characterized by comprising the screen including atransparent base member for reducing flexure of the screen, and adiffusing screen for imaging the image.

[0011] In order to achieve the above second object, the second inventionas claimed in claim 2, a table type display device comprising plural Mof projectors for projecting luminous flux to form an image, plural N ofreflection mirrors for bending optical path of luminous flux projectedfrom respective plural M of projectors, screen of horizontalinstallation type for projecting luminous flux for which optical path isbent, by the plurality of reflection mirrors N onto the predeterminedregion, respectively, characterized by comprising the screen including atransparent base member for reducing flexure of the screen, opticalsheet substantially for making luminous fluxes projected respectivelyfrom the plural M of projectors uniform, and a diffusing screen forimaging the image.

[0012] In order to achieve the above first object, the first inventionas claimed in claim 1 is, a table type display device comprising pluralM of projectors for projecting luminous flux to form an image, plural Nof reflection mirrors for bending optical path of luminous fluxprojected from respective plural M of projectors, screen of horizontalinstallation type for projecting luminous flux for which optical path isbent, by the plurality of reflection mirrors N onto the predeterminedregion respectively, characterized by comprising the screen including atransparent base member for reducing flexure of the screen, opticalsheet substantially for making luminous fluxes projected respectivelyfrom the plural M of projectors uniform, a diffusing screen for imagingthe image, transparent spread sheet for imaging the image, and coverplate for guarding the spread sheet.

[0013] It is preferable that the optical sheet is a Fresnel lens asdescribed in claim 4, a lenticular sheet as described in claim 5,consists of a lenticular sheet constituted by arranging lenses in onedirection of two dimensional directions of display surface of thediffusing screen and a lenticular sheet constituted by arranging lensesin the other direction of the two dimensional directions as described inclaim 6, and a bead screen as described in claim 7, or, a holographyscreen as described in claim 8, in order to make the luminous fluxesprojected from respective plural M of projectors uniform. Moreover, itis preferable that the optical sheet is constituted to form a scaledstructure by the transparent base member, the diffusing screen, and theabove screen frame as described in claim 19, in order to prevent theoptical sheet from expanding and contracting along with the moistureabsorption.

[0014] It is preferable that the transparent base member is a laminatedglass as described in claim 9, a thermal reinforced glass as describedin claim 10, or, an acrylic board as described in claim 11, in order toreduce the flexure of the above screen.

[0015] The diffusing screen formed by providing the diffused layer tothe laminated glasses described in claim 12, or the diffusing screenformed by providing the diffused layer to the thermal reinforced glassas described in claim 13, the diffusing screen formed by providing thediffused layer to an acryl plate as described in claim 14, is used forthe diffusing screen, in order to serve as a transparent screen and tosecure the safety at the time of breakage in case of using the glass asa component.

[0016] It is preferable that the above cover glass is a laminated glassas described in claim 14, or, a thermal reinforced glass as described inclaim 15, or an acryl plate as described in claim 17, in order to guardthe diffusing sheet at the glass breakage.

[0017] It is preferable that a predetermined amount of tension isapplied to the optical sheet and the diffusing sheet, as described inclaim 16, in order to prevent loosening.

[0018] It is preferable that the cover glass is arranged on the top ofthe device as described in claim 17, and is cemented to the screen frameto hold various members located on the lower layer of the cover glass,by the sealing material, in such a manner that in order to prevent thesurface of the screen from becoming dirty and from being damaged, and incase of spilling the liquid on the screen, to prevent the liquid frombeing made wraparound on the diffusing screen.

[0019] It is preferable that the cover glass is constituted to beexchangeable alone as described in claim 18, in order to make themaintenance excellent.

[0020] In the first invention, after the optical path is bent by theplural N of reflection mirrors, the luminous fluxes projectedrespectively of the plural M of projectors for projecting the luminousflux to form the image, are projected to a predetermined region of thescreen of the horizontal location type respectively, but the screencomprises the transparent base member for reducing the flexure of thescreen and the diffusing screen for imaging the image, so that even incase of making the screen large, the structure with few flexure of thescreen can be obtained. Therefore, table type display device can beprovided in such a manner that when the large screen display isperformed with the use of the screen having the structure with fewbending, the high resolution display can be achieved.

[0021] In the second invention, after the optical path is bent by theplural N of reflection mirrors, the luminous fluxes projectedrespectively of the plural M of projectors for projecting the luminousflux to form the image, are projected to a predetermined region of thescreen of the horizontal location type respectively, but the screencomprises the transparent base member for reducing the flexure of thescreen, the optical sheet for making luminous fluxes projectedrespectively of the plural M of projectors uniform substantially, andthe diffusing screen for imaging the image, so that even in case ofmaking the screen large, the structure with few flexure of the screencan be obtained, and the luminous flux projected to the diffusing screenis made uniform substantially. Therefore, table type display device canbe provided in such a manner that when a large screen display isperformed with the use of the screen having a structure with fewbending, the high resolution display, in which connection isunremarkable and it is easy to see, can be achieved.

[0022] In the third invention, after the optical path is bent by theplural N of reflection mirrors, the luminous fluxes projectedrespectively of the plural M of projectors for projecting the luminousflux to form the image, are projected to a predetermined region of thescreen of the horizontal location type respectively, but the screencomprises the transparent base member for reducing the flexure of thescreen, the optical sheet for making luminous fluxes projectedrespectively of the plural M of projectors uniform substantially, andthe transparent diffusing sheet for imaging the image, and the coverglass for guarding the diffusing sheet, so that even in case of makingthe screen large, the structure with few flexure of the screen can beobtained, and the luminous flux projected to the diffusing screen ismade uniform substantially. Therefore, table type display device can beprovided in such a manner that when the large screen display isperformed with the use of the screen having the structure with fewbending, the high resolution display, in which connection isunremarkable and it is easy to see, can be achieved.

BRIEF DESCRIPTION OF DRAWINGS

[0023]FIG. 1 is a cross-sectional view showing the structure of thetable type display device of the first embodiment according to thepresent invention;

[0024]FIG. 2 is a view illustrating the positional relation between theviewer and the screen in the table type display device of the firstembodiment;

[0025]FIG. 3 is a view explaining the reason for using the transparentbase member in the table type display device of the first embodiment;

[0026]FIG. 4 is a cross-sectional view showing the structure of thetable type display device of the second embodiment according to thepresent invention;

[0027]FIG. 5 is a view explaining the relation between the overlapportion on the screen and the visual performance when the overlapdisplay is performed in the table type display device;

[0028]FIG. 6 is a view explaining the same field characteristic demandedto the table type display device of large screen;

[0029] FIGS. 7 (a) and (b) are views illustrating the state of theluminous flux emanated from the screen, in the case that does not use anoptical sheet for screen of the table type display device, and in thecase that uses the optical sheet for screen of the table type displaydevice, respectively;

[0030]FIG. 8 is a cross-sectional view showing the structure of thetable type display device of third embodiment according to the presentinvention;

[0031]FIG. 9 is a cross-sectional view showing the structure of theprincipal portion of the table type display device of fourth embodimentaccording to the present invention;

[0032]FIG. 10 is a view showing the modified embodiment of the diffusingscreen of the table type display device according to a fourthembodiment;

[0033] FIGS. 11 (a) and (b) are the cross-sectional view showing thestructure of the principal portion of the table type display device offifth embodiment according to the present invention and view showing theexchangeable portion of the screen thereof, respectively;

[0034]FIG. 12 is a view showing the structure of the principal portionof the table type display device of sixth embodiment according to thepresent invention;

[0035]FIG. 13 is a view showing the structure of the principal portionof the table type display device of seventh embodiment according to thepresent invention;

[0036]FIG. 14 is a view showing the structure of the principal portionof the table type display device of eighth embodiment according to thepresent invention;

[0037]FIG. 15 is a view showing the structure of the principal portionof the table type display device of ninth embodiment according to thepresent invention;

[0038]FIG. 16 is a view showing the structure of the principal portionof the table type display device of tenth embodiment according to thepresent invention;

[0039]FIG. 17 is a view showing the structure of the principal portionof the table type display device of eleventh embodiment according to thepresent invention; and

[0040]FIG. 18 is a view explaining the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Hereafter, the embodiments of the present invention are explainedin detail with reference to the drawing. FIG. 1 is a cross-sectionalview showing a structure of the principal portion of the table typedisplay device of first embodiment according to the present invention.The table type display device according to the present embodimentcomprises, as shown in the FIG. 1, a plurality M of projectors 1L and 1Rof rear projection system (two in the shown embodiment) for projectingluminous flux to form an image, a plurality M of reflection mirrors 2Land 2R (N=M=2 in shown embodiment) for bending the optical path ofluminous flux projected from projectors 1L and 1R, respectively, ascreen 3 of the horizontal location type for projecting luminous fluxfor which optical path is bent by the reflection mirrors 2L and 2R onthe predetermined region, respectively, a casing 4 of table type forstoring respective constituent elements, a frame 5 connected in theinterior of the casing 4, and a screen frame 6 connected to the upperpart of the frame 5, and the above screen 3 comprises a transparent basemember 7 to reduce the flexure of the screen and a diffusing screen 8for imaging the image. The reflection mirrors 2L and 2R are supported tothe frame 5 or the like in the casing 4 by a support member (not shown).Moreover, in the case of horizontally locating the projectors 1L and 1R,the reflection mirrors 2L and 2R may use one large common mirror insteadof two reflection mirrors 2L and 2R.

[0042] The projectors 1L and 1R are supported horizontally with asupport member (not shown) in the casing 4. The projectors 1L and 1Rutilize a projector with high resolution, in this embodiment, aprojector with resolution of SXGA (1280*1024 pixels) is used, butinstead a projector with resolution of XGA (1024*768 pixels) may use.Moreover, the projectors 1L and 1R are arranged so as to projectluminous flux to the entire right and left half plane regions formed bydividing the diffusing screen 8 by two in back and forth direction ofFIG. 1, respectively. In this case, luminous flux may display withoverlap thereof in the adjacent portion of the half plane region, andmay display without the overlap, but in case of displaying luminous fluxwith overlap, the resolution in the entire display becomes small morethan two (2048*1280 pixels).

[0043] Transparent members such as the glass and acrylic resin can beused as the transparent base member 7, and a thermal reinforced glass oran acrylic board is used preferably. The thickness of the transparentbase member 7 is decided in consideration of the load added to the upperportion of the member 7, and assuming that the viewer gets on screen 3,the transparent base member 7 having thickness in such a manner that thescreen 3 does not flexure, is selected, when the total load that adds apredetermined margin to the average weight of the adult male for example(about 63 Kg) is loaded.

[0044] The diffusing screen formed by providing the diffused layer tothe laminated glass, or the diffusing screen formed by providing thediffused layer to the thermal reinforced glass, or the diffusing screenformed by providing the diffused layer to an acryl plate, is used forthe diffusing screen 8, in order to serve as a transparent screen and tosecure the safety at the time of breakage in case of using the glass asa component.

[0045] Moreover, in order to prevent the flaw from being formed on thesurface of the screen a glass or an acrylic plate with a hard coatingthereon may use as a component of the diffusing screen 8.

[0046] The table type display device according to the present embodimentis constituted in such a manner that for example, the side of the tablesurface formed in the upper part of the device (right and leftdirections shown in figure) is about 2000 mm, length (back and forthdirections shown in figure) is about 1600 mm, the height of the device(vertical direction shown in Figure) is about 1000 mm, and the size ofthe screen 3 is about 70 inches. Therefore, the positional relationbetween the viewer and the screen 3 of the table type display device isas shown in the FIG. 2.

[0047] Next, the operation of high resolution display at the time ofdisplaying large screen in the table type display device according tothe present embodiment is explained. Moreover, the case that does notperform the overlap display on the screen 3 is explained hereinafter,but in the case of performing the overlap display, “Image processingthat connects smoothly the image of the overlap portion” is only added.

[0048] First, with the use of an image formation device (not shown), thehigh resolution display data is formed by dividing the image to bedisplayed into the number of projectors (division by two in thisembodiment), and then respective these high resolution display data areoutputted with synchronization of projectors 1L and 1R.

[0049] Projectors 1L and 1R which receive the high resolution displaydata, are located in the casing 4 in such a manner that the projectionangle and projection distance shown in FIG. 1 are set, so that theoptical paths of respective luminous fluxes to form the imageshorizontally projected from the projectors 1L and 1R, are upward bent bythe reflection mirrors 2L and 2R. Luminous fluxes with bent optical pathare projected to the undersurface of screen 3, and are projected toright and left half plane regions of the diffusing screen 8 respectivelythrough the transparent base member 7. As a result, the display of thehigh resolution twice SXGA can be achieved on the large screen of about70 inches.

[0050] In this case, in the display device described in Japanese PatentApplication Opened No. 305079/2000 corresponding to the structure inwhich the transparent base member 7 is omitted from the screen 3 of thetable type display device according to the present embodiment, when thescreen bends as shown in FIG. 3, luminous fluxes from right and leftprojectors are not adjusted as a parallel light, so that the positionlooking as shadowy is caused since strength of light is differentaccording to the viewing position of the viewer. Therefore, in order toreduce the bending of the screen, the feature of constituting the screenwith the use of the transparent base member is necessary.

[0051] According to the table type display device of the presentembodiment, the screen 3 comprises the transparent base member 7 forreducing the bending of the screen 3 and the diffusing screen 8 forimaging the image, thereby constituting the large screen, so that thescreen 3 is not damaged even in the case that the viewer got on thescreen 3. Therefore, when large screen display is performed by using thescreen 3 having a structure with few bending, the high resolutiondisplay can be achieved.

[0052]FIG. 4 is a cross-sectional view showing a structure of the tabletype display device of second embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device of first embodiment shownin FIG. 1 so as to make the construction of the screen 3 changed, andthe portions other than the above are constituted same as the firstembodiment.

[0053] That is, the screen 3 of the present embodiment is constituted byinserting the optical sheet 9 with the function for making the luminousfluxes projected from respective projectors 1L and 1R uniform, betweenthe transparent base member 7 for reducing the bending of the screen andthe diffusing screen 8 for imaging the image. Any one of the Fresnellens, the Lenticular sheet, the beads screen or the holography screencan be used as the optical sheet 9. Moreover, in the present embodiment,the image is made easy to see further more by performing the overlapdisplay on the screen 3 and by performing “Image processing thatconnects smoothly the image of the overlap portion”.

[0054] In case of performing the overlap display, for example, as shownin FIG. 5, the overlap portions are caused in the shown verticaldirections and the right and left directions when luminous fluxes fromfour projectors are projected. At this time, in case of looking forwardstraight as shown by arrows a, b, and c, the viewer standing at theshown position looks the near side dark, and the far side dark,therefore, brightness becomes a<b<c. Moreover, according to viewingangle, in case of looking the right and left as shown by arrows d and e,the screen looks bright, and in case of looking straight as shown by thearrow b, the screen looks dark, therefore, brightness becomes b<d andb<e.

[0055] By the way, in case of constituting the table type display deviceof the large screen as in the present embodiment, when viewers standingat various positions as shown in FIG. 6, see the display image on thescreen, it is required that respective viewers have the same field anglecharacteristic. However, in case of performing the overlap display asshown in FIG. 7 (a), if it is constituted in such a manner that luminousfluxes from respective projectors are projected on the screen directly,in the overlap portion, the view point changes by observer's viewingangle, so that it will contradict the demand. Then, in this embodiment,as shown in FIG. 7(b), the device is constituted in such a manner thatluminous flux emanating the screen becomes substantially vertical to thescreen surface (in other words, becomes substantially parallel light),by using an optical sheet for making luminous fluxes substantiallyuniform as a component of the screen.

[0056] According to the table type display device of the presentembodiment, the optical sheet 9 is inserted between the transparent basemember 7 and the diffusing screen 8, the luminous flux incident on thediffusing screen 8 from the oblique direction emanates to the directionsubstantially orthogonal to the screen, therefore, the luminous fluxprojected on the diffusing screen 8 is made uniform substantially, sothat the connecting portion of right and left half plane regions becomesdark, and the connection becomes unremarkable, and thus the view of theimage does not change at different standing positions of the viewer.Therefore, when the large screen display is performed by using thescreen 3 having the structure with few bending, the high resolutiondisplay, in which connection is unremarkable and it is easy to see, canbe achieved.

[0057]FIG. 8 is a cross-sectional view showing a structure of the tabletype display device of third embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device of second embodimentshown in FIG. 4 so as to make the construction of the screen 3 changed,and the portions other than the above are constituted same as the secondembodiment.

[0058] That is, in this embodiment, as an optical sheet being thecomponent of the screen 3, a sheet constituted by stacking a lenticularsheet 9-1 formed by arranging lens to one direction (X direction in FIG.8) in two dimensional directions of display surface of the diffusingscreen 8, and a lenticular sheet 9-2 formed by arranging lens to theother direction (Y direction in FIG. 8) of two dimensional directions ofthe diffusing screen 8, is used, instead of one optical sheet. Moreover,in the present embodiment, it becomes easy to see the image furthermore, by performing the overlap display on the screen 3, and byperforming “Image processing that connects smoothly the image of theoverlap portion”

[0059] According to the table type display device of the presentembodiment, the optical sheet 9 consisting of lenticular sheets 9-1 and9-2 is inserted between the transparent base member 7 and the diffusingscreen 8, the luminous flux incident on the diffusing screen 8 from theoblique direction emanates to the direction substantially orthogonal tothe screen, therefore, the luminous flux projected on the diffusingscreen 8 is made uniform substantially, so that the connecting portionof right and left half plane regions becomes dark, and the connectionbecomes unremarkable, and thus the view of the image does not change atdifferent standing positions of the viewer. Therefore, when the largescreen display is performed by using the screen 3 having a structurewith few bending, the high resolution display, in which connection isunremarkable and it is easy to see, can be achieved.

[0060]FIG. 9 is a cross-sectional view showing a structure of theprincipal portion of the table type display device of fourth embodimentaccording to the present invention.

[0061] The table type display device according to this embodiment ismade a change to the table type display device of third embodiment shownin FIG. 8 so as to make the construction of the screen 3 changed, andthe portions other than the above are constituted same as the thirdembodiment.

[0062] That is, in this embodiment, instead of one piece diffusingscreen 8 used to constitute the top of the screen 3 in the thirdembodiment, the screen structure is changed to use a diffusing screen 12consisting of a transparent diffusing sheet 10 for imaging the image anda cover glass 11 for guarding the diffusing sheet 10, and to add asuppression board 13 to the upper portion of the periphery of the coverglass 11. Moreover, in this embodiment, though the optical sheet 9consisting of two lenticular sheets 9-1 and 9-2 as shown in FIG. 9, isused as an optical sheet 9, one piece optical sheet 9 may be usedinstead thereof.

[0063] In addition to the structure in which the diffusing sheet 10 andthe cover glass 11 as shown in FIG. 9 are independently provided, thediffusing screen 12 may be made a structure in which a diffused layer 15is formed to the undersurface of a laminated glass 14 used as the coverglass 11 as shown in FIG. 10. In addition, though it is not shown inFigure here, the diffused layer is formed to the undersurface of thethermal reinforced glass used as the cover glass 11.

[0064] According to the table type display device of the presentembodiment, in addition to obtain the effect similar to the thirdembodiment, the diffusing screen 12 consisting of the diffusion sheet 10and the cover plate 11 was used instead of one piece diffusing screen 8,so that the manufacturing cost of the screen 3 can be reducedconsiderably compared with the case utilizing the sapphire glass etc.having high hardness. In addition, the cover plate 11 was provided onthe surface of the screen 3, so that the surface of the screen can beprevented from becoming dirty and being damaged.

[0065] FIGS. 11(a) and 11(b) are a cross-sectional view showing thestructure of the principal portion of the table type display device offifth embodiment of the present invention and a view showing theexchangeable portion of the screen, respectively. The table type displaydevice according to this embodiment is made a change to the table typedisplay device of fourth embodiment shown in FIG. 9 so as to make theconstruction of making a part of the screen 3 exchangeable, and theportions other than the above are constituted same as the fourthembodiment (using one piece of the optical sheet 9).

[0066] That is, in this embodiment, as shown in FIG. 11(a), by providinga rubber sheet 16 between cover glass 11 and the suppression board 13,the cover glass 11 can be exchanged and unitized by cementing contactportion of upper surface of the rubber sheet 16 and undersurface of thesuppression board 13, Contact portion of undersurface of the rubbersheet 16 and upper surface of the cover glass 11, and contact portion ofouter peripheral surface of the rubber sheet 16 and inner peripherysurface of the screen frame 6, by the sealing material respectively.Moreover, as the optical sheet 9, one piece of the optical sheet 9 isused in FIG. 11(a), but instead thereof, the optical sheet 9 consistingof two lenticular sheets 9-1 and 9-2 as shown in FIG. 9 may be used.Moreover, a seal member may be used instead of the rubber sheet.

[0067] According to the table type display device of the presentembodiment, in addition to obtain the effect similar to the fourthembodiment, as shown in FIG. 11(b), in case of

the liquid on the cover glass 11 constituting the diffusing screen 12,the effect of effectively preventing the liquid from being turned underthe diffusing screen 12, can be obtained. In addition, it is astructure, in which cover glass 11 can be exchanged alone, so that theeffect of achieving excellent maintenance is obtained.

[0068]FIG. 12 shows a structure of the principal portion of the tabletype display device of the sixth embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device (using one piece of theoptical sheet 9) of fourth embodiment shown in FIG. 9 so as to make thediffusing sheet 10 and the optical sheet 9 being the constructionalelement of the screen 3 predetermined tension, and the portions otherthan the above are constituted same as the fourth embodiment.

[0069] That is, in this embodiment, as shown in FIG. 12, a downwardtension corresponding to a weight 18 is applied by extending diffusingsheet 10 and optical sheet 9 to the right and left directionsrespectively, by folding the extending portion downward through acylindrical member 17, and by hanging a weight 18 on the right and leftbottom portions, respectively.

[0070] According to the table type display device of the presentembodiment, in addition to obtain the effect similar to the thirdembodiment, Up the loosing of the diffusing sheet 10 and the opticalsheet 9 are prevented, and thus the effect of preventing the entirescreen 3 from loosening can be achieved.

[0071]FIG. 13 shows a structure of the principal portion of the tabletype display device of the eighth embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device according to sixthembodiment shown in FIG. 12, in such a manner that the portionsextending to the shown right and left directions of the spread sheet 10and the optical sheet 9 are made reduced, and the extended portions arefixed by a sheet stopper 19 and the portions other than the above areconstituted same as the sixth embodiment.

[0072] According to the table type display device of the presentembodiment, in addition to obtain the effect similar to the sixth abovesixth embodiment, a necessary number of the cylindrical material 17 andthe weight 18 becomes half the sixth embodiment, so that the effect ofobtaining reduction in costs is achieved.

[0073]FIG. 14 shows a structure of the principal portion of the tabletype display device of the eighth embodiment according to the presentinvention. The table type display device of the present embodiment is adevice changed in such a manner that, to the table type display deviceof sixth embodiment shown in FIG. 12, the part that extends in the rightand left directions of the spread sheet 10 and the optical sheet 9, ismade a minimum size, and a weight 18 is hung on the edge of a sandwichmember 20 by pinching the extended portion by sandwich member 20consisting of two board members, and the portions other than the aboveare constituted same as the sixth embodiment.

[0074] According to the table type display device of this embodiment, inaddition, the effect similar to the above sixth embodiment can beachieved, and the effect of preventing the stress concentration to rightand left edges of the spread sheet 10 and the optical sheet 9 in case ofusing two weights 18, respectively, can be obtained.

[0075]FIG. 15 shows the structure of the principal portion of the tabletype display device according to the ninth embodiment of the presentinvention. The table type display device according to this embodiment ischanged in such a manner that the parts extending to the right and leftdirections of the spread sheet 10 and the optical sheet 9, are made aminimum size for the table type display device according to sixthembodiment shown in FIG. 12, and a number of weights 18 (5 pieces in theshown embodiment respectively) are hung on the extended portions,directly, and the portions other than the above are constituted same asthe sixth embodiment.

[0076] According to the table type display device of the presentembodiment, the effect similar to the sixth embodiment can be obtainedand the structure thereof can be simplified.

[0077]FIG. 16 shows a structure of the principal portion of the tabletype display device of the tenth embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device of sixth embodiment shownin FIG. 12 constituted in such a manner that the tension is applied tothe two arms in the right and left of the spread sheet 10 and theoptical sheet 9, so as to apply the tension to the four arms in thefront, back, left and right of the spread sheet 10 and the optical sheet9 shown in FIG. 16, and the portions other than the above areconstituted same as the sixth embodiment.

[0078] According to the table type display device of the presentembodiment, the effect similar to the sixth embodiment can be obtainedand the loose prevention function of the screen comes to be strengthenedfurther.

[0079]FIG. 17 shows a structure of the principal portion of the tabletype display device of the eleventh embodiment according to the presentinvention. The table type display device according to this embodiment ismade a change to the table type display device of fifth embodiment shownin FIG. 11 so as to make the optical sheet 9 a sealed structure, and theportions other than the above are constituted same as the fifthembodiment.

[0080] That is, in this embodiment, as shown in FIG. 17, a rubber 21 isprovided between the upper surface of the diffusing screen 12 and theundersurface of the suppression board 13, and a rubber 22 is providedbetween a right and left edge under the transparent base member 7 andupper surface of the screen frame 6, and then a contact section of edgesurface of the rubber 21 and upper surface of the diffusing screen 12, acontact section of the undersurface of the rubber 21 and upper surfaceof the screen frame 6, and a contact section of upper surface of therubber 22 and undersurface of the transparent base member 7 are cementedrespectively by an adhesive seal 23, so that the optical sheet 9 is madea complete sealed structure.

[0081] According to the table type display device of this implement, inaddition that the effect similar to the fifth embodiment can beobtained, the effect of effectively preventing expansion and contractionof an optical sheet due to the moisture absorption thereof in case ofusing the sheet made of the acrylic fiber as an optical sheet, can beobtained.

[0082] Here, the thickness of the diffusing screen of the transparentbase member (base glass), the cover glass and the glass base inrespective embodiments is explained.

[0083] The image projected from the projector through the reflectionmirror reaches an optical sheet by the passage of the base glass. Atthis time, the direction of projection of the image changes only by therefraction index of the glass when the image passes through the baseglass, but the imaging is not performed in the base glass portion, sothat even though the direction of the projection changes if theprojector is adjusted so as to focus the image on the diffused layer,the influence by the refraction index of the above glass disappears.Therefore, the thickness of the base glass can be arbitrarily selected,and can be decided based on “Strength when the person has gotten on upby the error” or the like which is required to the table. For example,in the case of screen of about 70 inches, assuming that the load ofabout 100 kg is received to the center of the screen, if the laminatedglass of the thickness of about 6 mm+about 6 mm is used, the glasshaving thickness below the allowable stress can be selected.

[0084] On the one hand, the thickness of the glass of the diffused layeron the optical sheet has a problem that When the direction of lightchanges, it becomes difficult to see the image due to the refractionindex of the glass, since the image after imaging passes through theglass. In the display device where the screen is located vertically, thescreen is often seen in the front or the front near, so that theinfluence of refraction index is a little, but in the case of the tabletype display device, the screen is always seen from the direction of theoblique, so that the far side of the screen is susceptible to theinfluence of refraction index, as compared with the near side of thescreen, and as a result, the image is distorted. Moreover, even thoughthe rule is put on the glass, and the case that the length of the saidpicture data is also measured, the length is hardly measured since theimaged plane is separated and the image refracts to see. Up to now, whenthe measurement of length to several thicknesses of the glass are tried,the thickness of glass layer on the surface has a limit of about 12 mm,and the result of measurement is that the thinner, the thickness, thebetter. There is a problem that the device cannot be manufactured by thescreen having the size of about 70 inches when the glass is too thin,too, so that it was identified that the laminated glass of about 2mm+about 2 mm−about 6 mm+about 6 mm is suitable as the glass of the toplayer. Moreover, even in the case of a thermal reinforced glass and anacrylic, similar thickness is suitable.

[0085] In the above described embodiment, though the present inventionwas explained with a plurality of projectors and an a plurality ofreflection mirrors, the present invention is not limited to theseembodiments, and thus the present invention can be applied to a singleprojector and a single reflection mirror.

What is claimed is:
 1. A table type display device comprising plural Mof projectors for projecting luminous flux to form an image, plural N ofreflection mirrors for bending optical path of luminous flux projectedfrom respective plural M of projectors, screen of horizontalinstallation type for projecting luminous flux for which optical path isbent, by the plurality of reflection mirrors N onto the predeterminedregion, respectively, characterized by comprising the screen including atransparent base member for reducing flexure of the screen, and adiffusing screen for imaging the image.
 2. A table type display devicecomprising plural M of projectors for projecting luminous flux to forman image, plural N of reflection mirrors for bending optical path ofluminous flux projected from respective plural M of projectors, screenof horizontal installation type for projecting luminous flux for whichoptical path is bent, by the plurality of reflection mirrors N onto thepredetermined region, respectively, characterized by comprising thescreen including a transparent base member for reducing flexure of thescreen, an optical sheet substantially for making luminous fluxesprojected respectively from the plural M of projectors uniform, and adiffusing screen for imaging the image.
 3. A table type display devicecomprising plural M of projectors for projecting luminous flux to forman image, plural N of reflection mirrors for bending optical path ofluminous flux projected from respective plural M of projectors, screenof horizontal installation type for projecting luminous flux for whichoptical path is bent, by the plurality of reflection mirrors N onto thepredetermined region, respectively, characterized by comprising thescreen including a transparent base member for reducing flexure of thescreen, an optical sheet substantially for making luminous fluxesprojected respectively from the plural M of projector uniform, adiffusing screen for imaging the image, transparent spread sheet forimaging the image, and cover plate for guarding the spread sheet.
 4. Atable type display device as claimed in claim 2, wherein the opticalsheet is a Fresnel lens.
 5. A table type display device as claimed inclaim 2, wherein the optical sheet is a lenticular sheet.
 6. A tabletype display device as claimed in claim 2, wherein the optical sheetcomprises first lenticular sheet having lenses arranged in one directionin two dimensional directions of display surface of the diffusingscreen, and, second lenticular sheet having lenses arranged in a otherdirection in two dimensional directions thereof.
 7. A table type displaydevice as claimed in claim 2, wherein the optical sheet is a beadsscreen.
 8. A table type display device as claimed in claim 2, whereinthe optical sheet is a holography screen.
 9. A table type display deviceas claimed in claim 1, wherein the transparent base member is alaminated glass.
 10. A table type display device as claimed in claim 1,wherein the transparent base member is a thermal reinforced glass.
 11. Atable type display device as claimed in claim 1, wherein the transparentbase member is an acryl plate.
 12. A table type display device asclaimed in claim 1, wherein the diffusing screen is a diffusing screenconstructed by installing the diffused layer in the laminated glass. 13.A table type display device as claimed in claim 1, wherein the diffusingscreen is a diffusing screen constructed by installing the diffusedlayer in the thermal reinforced glass.
 14. A table type display deviceas claimed in claim 1, wherein the diffusing screen is a diffusingscreen constructed by installing the diffused layer in the acryl plate.15. A table type display device as claimed in claim 3, wherein the coverplate is a laminated glass.
 16. A table type display device as claimedin claim 3, wherein the cover plate is a thermal reinforced glass.
 17. Atable type display device as claimed in claim 3, wherein the cover plateis an acryl plate.
 18. A table type display device as claimed in claim3, wherein the tension of the given amount is applied on the opticalsheet and the diffusion sheet.
 19. A table type display device asclaimed in claim 3, wherein the cover plate is arranged on the top ofthe devices, and is cemented to a screen frame for holding variousmembers arranged on the lower layer of the cover glass, by sealingmaterial.
 20. A table type display device as claimed in claim 3, whereinthe cover plate is made to be a structure capable of being exchangedalone.
 21. A table type display device as claimed in claim 2, whereinthe optical sheet is constructed so as to form a sealed structure withthe transparent base member, the diffusing screen, and the screen frame.22. A table type display device comprising a projector for projectingluminous flux to form an image, a reflection mirror for bending opticalpath of luminous flux projected from the projector, a screen ofhorizontal installation type for projecting luminous flux for which anoptical path is bent, by the reflection mirror onto the predeterminedregion, characterized by comprising the screen including a transparentbase member for reducing flexure of the screen, and a diffusing screenfor imaging the image.
 23. A table type display device comprising aprojector for projecting luminous flux to form an image, a reflectionmirror for bending optical path of luminous flux projected from theprojector, a screen of horizontal installation type for projectingluminous flux for which an optical path is bent, by the a reflectionmirror onto the predetermined region, characterized by comprising thescreen including a transparent base member for reducing flexure of thescreen, an optical sheet substantially for making luminous fluxprojected from the projector uniform, and a diffusing screen for imagingthe image.
 24. A table type display device comprising a projector forprojecting luminous flux to form an image, a reflection mirror forbending optical path of luminous flux projected from the projector, ascreen of horizontal installation type for projecting luminous flux forwhich an optical path is bent, by the reflection mirror onto thepredetermined region, characterized by comprising the screen including atransparent base member for reducing flexure of the screen, an opticalsheet substantially for making luminous fluxes projected from theprojector uniform, a diffusing screen for imaging the image, atransparent spread sheet for imaging the image, and cover plate forguarding the spread sheet.